Within the framework of nonrelativisitic QCD factorization formalism, we present the next-to-leading-order relativistic corrections to $Υ$ exclusive decay into $η_c$ plus $J/ψ$. The double charmonia can be produced through several immediate channels, i.e. $Υ\to g^*g^*g^*\to η_c+J/ψ$, $Υ\to g^*g^*γ^*\to η_c+J/ψ$, and $Υ\to γ^*\to η_c+J/ψ$. The amplitudes of these three channels are obtained accurate up to ${\cal O}(α_s^3 v^2)$, ${\cal O}(αα_s^2 v^2)$, and ${\cal O}(αα_s^2 v^2)$ respectively, where $v$ indicates the typical heavy quark velocity in bottomonium and/or charmonium rest frame. The decay rates are also presented. We find the next-to-leading-order relativistic corrections to the short distance coefficients as well as the decay rates are both significant and negative, especially for the corrections from bottomonium. More seriously, the decay rates are even brought into negative by including the relativistic corrections, which indicates the poor convergence for the velocity expansion in this kind of processes. Detailed analysis is given in the paper.
We study exclusive production of scalar $χ_{c0}\equiv χ_c(0^{++})$ and pseudoscalar $η_c$ charmonia states in proton-proton collisions at the LHC energies. The amplitudes for $gg \to χ_{c0}$ as well as for $gg \to η_c$ mechanisms are derived in the $k_{T}$-factorization approach. The $p p \to p p η_c$ reaction is discussed for the first time. We have calculated rapidity, transverse momentum distributions as well as such correlation observables as the distribution in relative azimuthal angle and $(t_1,t_2)$ distributions. The latter two observables are very different for $χ_{c0}$ and $η_c$ case…
This paper is devoted to the leading twist exclusive bottomonia decays with double charmonium in the final state. Using models of the twist-2 charmonia distribution amplitudes the widths of these decays are calculated within light cone formalism. In addition, the processes under consideration are studied within nonrelativistic QCD. In our analysis we have found that the production of some of the $P$-wave charmonia mesons with $L_z \neq 0$ is allowed already at the leading twist approximation. This means that the selection rules which predict the suppression of such decays are violated. The mec…
LCSR analysis of exclusive two-body B decay into charmonium
我们分析了B -> K H_c（其中H_c = eta_c，J/psi，chi_{cJ(J=0,1)}）衰变，估计了光锥求和规则（LCSR）的不可因式分解贡献.对于B -> K J/psi，特别是对于B -> K chi_{c1}衰变，不可因式分解的贡献是相当大的。对于B衰变成一个（伪）标量charmonia，我们发现小的nonfactorizable的贡献，不能容纳相对较大的分支比的测量。这特别关系到令人困惑的B -> K chi_{c0}衰变。
We investigate the two-photon transitions $H_{c\bar c} \to γ^*γ$ of the charmonium system in light-front dynamics. The light-front wave functions were obtained from solving the effective Hamiltonian based on light-front holography and one-gluon exchange interaction within the basis light-front quantization approach. We compute the two-photon transition form factors as well as the two-photon decay widths for S- and P-wave charmonia, $η_c$ and $χ_{cJ}$ and their excitations. Without introducing any free parameters, our predictions are in good agreement with the recent experimental measurements b…
We calculate the decay branching fractions of the Higgs boson to $J/ψ$ and $η_c$ via the charm-quark fragmentation mechanism for the color-singlet and color-octet states in the framework of non-relativistic QCD. The decay rates are governed by the charm-quark Yukawa coupling, unlike the decay $H\to J/ψ+ γ$, which is dominated by the $γ^*$-$J/ψ$ mixing. We find that the decay branching fractions can be about $2 \times 10^{-5}$ for $H\to c{\bar c}+J/ψ$, and $6 \times 10^{-5}$ for $H\to c{\bar c}+η_c$. We comment on the perspective of searching for the Higgs boson to $J/ψ$ transition at the High-…
In this work, we study the exclusive decay of $Υ$ into $J/ψ$ in association with $η_c$ ($χ_{c0,1,2}$). The decay widths for different helicity configurations are evaluated up to QCD next-to-leading order within the nonrelativistic QCD framework. We find that the QCD corrections notably mitigate the renormalization scale dependence of the decay widths for all the processes. The branching fraction of $Υ\rightarrow J/ψ+χ_{c1}$ is obtained as $3.73^{+5.10+0.10}_{-2.06-1.19}\times 10^{-6}$, which agrees well with the Belle measurement, i.e., ${\rm Br}(Υ\rightarrow J/ψ+χ_{c1})=(3.90\pm1.21\pm0.23)\t…
Exclusive Nonleptonic Decays of Bottom and Charm Baryons in a Relativistic Three-Quark Model: Evaluation of Nonfactorizing Diagrams
在相对论性三夸克模型中研究了底重子和粲重子的非轻子衰变，模型中重子-三夸克顶点的动量依赖性为高斯形状。我们包括因式分解以及非因式分解贡献的衰减幅度。对于重到轻的跃迁Q -> q u d，非因式分解图的总贡献在振幅上达到因式分解贡献的约60%，对于b -> c u d跃迁，非因式分解图的总贡献达到约30%。我们计算各种非轻子衰变的速率和极化不对称参数，并将它们与现有数据和其他模型计算的结果进行比较。
After the great triumph of the Higgs discovery in 2012, the next target at the energy frontier will be to study the Higgs properties and to search for the next scale beyond the SM. Experimentally, the $H\to c \bar{c}$ channel would be extremely difficult to dig out because of both the weak Yukawa coupling and the daunting SM di-jet background. We propose to test the charm-quark Yukawa coupling at the LHC and future hadron colliders with the Higgs boson decay to $J/ψ$ via the charm-quark fragmentation. Using the non-relativistic quantum chromodynamics (NRQCD), we study the charmonia production …
